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(No Model.) 2 Sheets-Sheet 1.. G. GRASSER. METHOD OF AND APPARATUS FORMAKING DIES. No. 426,375.

Patented Apr. 22, 1890.

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'2 Sheets-Sheet 2. G. GRASSBR. METHOD OF AND, APPARATUS FOR MAKING DIES.No. 426,375.

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Patented Apr. 22', 189.0.

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UNITED STATES PATENT OFFICE.

CHARLES GRASSER, OF PASSAIC, NEIV JERSEY, ASSIGNOR TO THE SMITH BROTHERSMANUFACTURING COMPANY, OF SAME PLACE.

METHOD OF AND APPARATUS FOR MAKENG DIES.

SPECIFICATION forming part of Letters Patent No. 426,375, dated April22, 1890.

Application filed July 29, 1889. Serial No. 319,081. (No model.)

To all whom 112'; may concern.-

Be it known that I, CHARLES GRASSER, a citizen of the United States,residing at Passaic, county of Passaic, in the State of New Jersey, haveinvented a new and useful Method of and Apparatus for Producing Dies forStamping and Embossing Sheet Metal, of which the following is aspecification.

My invention relates to a new and useful art or method of constructingdies for the striking up or embossing of sheet metal by founding orcasting such dies of an aluminium bronze or alloy, which at a smallfraction of the cost of cut sunk steel dies is their full equal inperfection of finish and their superior in endurance.

From time immemorial down to the present day dies for stamping andembossing sheet metal have been and continue to be laboriously dug outof steel blocks by the class of artistic mechanics known as diesinkers.Die-sinking in its highest depart ments requires a combination oftalents, natural and acquired, which commands extremely high wages tothe few who possess them. The process of engraving in reverse is slowand hazardous at best, a single mislick often ruining months of mostskillful and painstaking labor. Being compelled to cut a desired designin reverse, or intaglio, makes the task peculiarly diiliicult,especially with large deep dies having elaborate patterns. For thisreason ornamented articles produced by stamping or pressing have, as arule, a stiff appearance. Theylack thegraceful and artistic finish whichcharacterizes a work produced in relief by a skillful chaser or repoussworker.

On account of the great cost of steel dies cut into a solid block,suporadded to the lastmentioned diiiiculty, attempts. have been made toproduce such dies by casting them in the rough of iron, steel, orhard-metal compositions and finishing them afterward. by the labor ofthe die-sinker. This mode of making dies carries with it defects whichonly too often prove that such dies are of inferior finish andendurance. The following explanation will make this clear. The thickheavy blocks of metal which are required for such dies cannot be cast byany of the present known methods with such perfection and sharpness offine outlines of the design as such dies require. has to be worked overand finished by the die-sinker, which involves nearly as much work ascutting it into solid block. Then it often happens that while workingover and finishing a cast die the die-sinker finds underneath theapparently solid surface porous spots or bad places, which render thedie useless, and the work so far done is lost. Such a discovery may notbe made until the die is almost finished. Another not infrequent sourceof loss of steel dies is the destruction of the die in thehardening-bath. By means of my invention 1 overcome all the statedexisting difficulties and produce dies of a hardness and strength equalto a forged and sunk steel die and obtain a perfection and sharpness ofdesign equal to the artists handwork. By copying my dies from a patternworked in relief by the chaser or repouss worker I reproduce in intaghothe same perfection in design as imparted to the relief.

I will now describe with reference to the accompanying drawings mymethod of producing perfect dies and molds by means of casting andpressure, using for that purpose an apparatus of peculiar construction.

In said drawings, Figure 1 is a vertical sectional view of an apparatusfor carrying out my invention. Fig. 2 is a perspective view thereof.Fig. 3 is an under side "iew of the pattern and its frame. Fig. 4 is avertical sectional view of the complete apparatus.

The apparatus comprises three principal parts A C E, of cast-iron. orother cast metal, each having a distinct function.

A is a frame of such internal shape and size as I desire to give to thedie. In the drawings this frame is shown tapering upward toward the opentop or mouth, so that dies cast therein will have the customary taperingbody. The frame A is provided with an interior lining B of refractorynon-conducting material, prefeably either asbestus orcrucible clay. Thislining is applied about one-sixteenth of an inch thick. The frame aserves as the mceptacle for the fluid metal,

The design (in intaglt'o) and at the same time answers as the mold togive shape to the body of the die to be cast. The lining B serves toprevent the too rapid cooling of the fluid metal, so as to allow timefor the necessary operation of filling the open mold nearly to its brimwith molten metal, (aluminium alloy,) removing the dross and otherimpurities, promptly closing the open mouth of the mold, with thepattern (face downward) clamping said pattern tightly down. upon theasbestus gasket or packing,

so as to close the mouth of the mold, and finally forcing the molten orplastic metal into close and intimate juxtaposition with the pattern bypiston-pressure from below, all as hereinafter fully explained.

C is another frame, provided with one flange 0, extending outward to theouter edge of frame A, and another flange 0, extending inward, so thatwhen the frame 0 is attached to frame A by means of screws the saidflange 0' forms a portion of a floor or bottom to frame A.

E is a block or piston of such size as to pass loosely through the upperopening of frame 0, and to thus constitutea false bottom and completethe floor of frame A.

D is another block, which is superimposed upon the block E. The block Dis kept in place on the piston E by means of'two dowelpins 6. The blockE serves as a plunger or piston, by means of which pressure can beapplied to the fluid metal when such is poured in and inclosed in frameA. The block D, resting on block E, as indicated, and being forced toenter the mold, as shown in Fig. 4, serves the purpose of taking up thecentral shrinkage of the metal and insures a perfect counterpartimpression of the pattern.

The metal composition which I prefer to use for my said dies is acomposition or alloy of ten per cent. aluminium and ninety per cent.copper. This composition has extremehardness, and when founded under mymethod forms a perfect counterpart of the pattern.

My present invention is largely directed to obtaining a full andaccurate impression of the pattern, notwithstanding the tendency of suchcomposition to contract bodily in setting and unequally in differentparts of the mass.

To compensate for the slower cooling of the center, and consequently atthe place forlast contraction, I use the block D. As stated above, saidblock being slightly smaller in cross-section than the bottom opening ofthe frame A it can be forced into the center of the fluid metal duringits different stages of cooling until it becomes solidified. As thecomposition of which the die is made shrinks more than the block D,which is made of castiron, the said block becomes as firmly held as ifit had been of the same substance with the die, and so remains anintegral part thereof.

One or more downward ly-flared holes (1 may be provided in the blockD toreceive portions of the molten metal to still further lock the partstogether.

The space between the piston E and the frame (3 serves to receive afire-proof packing or gasket F for the piston E, which is made byramming asbestus fiber in the space around said piston. The packing Fserves the purpose of preventing the escape of fluid metal from thereceptacle or mold A when a high pressure is applied to if.

G is a plain iron frame, which is of the same size onthe outside edge asthe frameA on its upper edge. The inside of frame G is about one-half ofan inch from the inside edges of frame A. The function of the frame G isto strengthen and hold the relief-pattern H, from which an impression isto be taken, thereby obtaining the intaglio of the pattern.

The relief-pattern H is made of fine plastic clay and burned or baked ashard as what is called by potters biscuit-ware. This clay pattern H isso formed as to have a fiat base or back It. The base or back is exactlyof the same thickness as the frame G and a little smaller than theinside of the frame, so that the pattern forming one piece with its basecan be placed inside of the frame, leaving about one-eighth of an inchspace between the frame and the pattern-base. This space is filledcarefully withplaster-of paris, thereby cementing the pattern-basefirmly in the frame. When the pattern is thus united with the frame G, astrip of asbestus sheathing is pasted around the edge of the face sideto form a packing or gasket J between frame A and frame G when thelast-named is placed face down on frame A, as is indicated by thedrawing Fig. 4.

After cementing the burnt clay pattern H in the frame G and providingthe packingstrips J on the face side the pattern is again well dried toexpel all, moisture before using it for the impression.

The frame G has two steady or dyowel pins g on opposite corners. Thesepins gt loosely in corresponding holes a in the top edge of frame A, soas to permit expeditious and accurate placing of the frame G, with itspattern, in the desired position on the frame A, thus completing a moldfor a die to be cast.

The. frame G is useful in protecting the somewhat fragile material ofthe pattern IIO proper from excessive pressure between the mold andplaten.

Four spiral springs Kone at each corner of the apparatusserve thepurpose of giving a certain but yielding resistance to the combinedframes A, O, and G when pressure is applied on the top. This resistanceof the springs is usually very desirable, although under certainmodifications of the apparatus it maybe dispensed with.

As seen by the drawings, the whole apparatus rests on the piston E,which is somewhat longer than the depth of packing frame C, which isonly prevented from slipping down over the piston E by the friction ofthe packing F. It is, however, necessary that the combined frames 0 andA, with the pattern-frame G on top, should not move down against thestationary piston until the frame A, forming the mold-walls, is filledwith fluid metal from the top and the pattern in frame G has been placedface downward on the same as a cover for the final completion of themold. The resistance of the springs K mustfor this reason beconsiderably more than the combined weight of the frames and metal.

The pattern in its frame G, when laid on the filled mold,'is preventedfrom moving laterally by two steady-pins g.

If the metal-receptacle A is filled and the pattern placed on top as afinal cover, (which must be done expeditiously, because refractorymetals congeal very rapidly when once poured from the meltingpot,) it isself-evident that no avoidable time should be lost by fastening theframe G firmly to the frame A, so as to prevent the escape of the fluidmetal when pressure is applied to it, which is accomplished in my caseby placing the whole filled apparatus under a suitable screw-pressplaten P and forcing the combined mold and pattern downward against thepiston E. The surplus resistance of the springs requires a correspondingpressure which is exercised on the frame G, thereby pressing it tightlyon the frame A, preventing the escape of the fluid metal.

It may appear at first sight a rather peculiar mode of procedure toforce the metalreceptacle downward. It might seem more practical to havethe pattern in frame Gfastened at the bottom of the receptacle and pourthe fluid metal on the pattern, and then apply the pressure by forcingthe piston downward in the metal. However, the great importance ofmaking and manipulating the apparatus as I describe it will presently beclearly seen.

The production of the clay pattern requires little description, becausethere are several ways to make fine perfect copies from relief designsin plastic clay well known to artisans skilled in the production ofornamented goods made of plastic material. I prefer to take a fineperfect plaster-of-paris mold from the original relief-pattern,which maybe modeled in wax or be carved in wood, metal, or other.

suitable substance by the artistic chaser or repouss worker. From such aplaster mold, when well dried, I take fine perfect impressions inplastic clay and harden them by burning in a furnace to the requireddegree.

Before proceeding to describe the final operation in casting a die withthe apparatus described in this specification a few explanations will begiven concerning metal compositions used for casting dies and molds, andbrief reference made to some of the properties of the above=mentionedal'uminium and copper composition, which I prefer for the material ofsuch cast dies.

1 have heretofore in actual practice cast many dies and molds ofcast-iron, of phosphor-bronze, of bell-metal, of aluminium bronze, andeven of steel; but I have made such castings by other more familiarmethods and by means of other apparatus for applying pressure to thefluid metal, the results of which were not so satisfactory.

In the customary method of pouring the molten metal through gates orsprues into a closed mold several serious difficulties arise. Forexample, the stream of molten metal is liable to break down or partiallyobliterate the smaller saliencies in the mold-face. Again, the dross andother impurities form askin or crust which intervenes between the metaland the mold-face and prevents the taking of a sharp impression. Of themetals above cited the first three have not sufiicient strength andhardness to resist the high crushing-pressure required in dies forstamping and embossing metals or pressing other tough materials into therequired shape.

Cast-steel, on the other hand, on account of its liability to set exceptat the extremely high temperature required to melt it, does not castvery sharp nor with even perfect surfaces. The high heat of moltensteel, moreover, bites into the pattern, even when the latter is made ofthe most refractory clay.

It should further be borne in mind that aluminium bronze of the statedmixture is a composition presenting many peculiar features when cast inmassive blocks. Metals when poured in a mold in the ordinary way,

or when forced in a mold by pressure from an injecting apparatus, arenecessarily brought into a state of agitation. In some of the metals andcompositions such agitation produces no serious results, because thespattering fragments of metal on entering the mold reunite perfectlywith the mass and the casting shows no signs that such spattering ortemporary division had taken placegbut in casting aluminium bronze theabove-mentioned agitation, spatterin g, and divisionof the metal whileentering the mold produce serious defects in the cast-ing. The scatteredor divided portions (perhaps owing to superficial oxidation) do notunite perfectly again, and the whole surface, and even the interiorportion of the casting, is full of defects, presenting an appearance asif the metal had been loaded with impurities 5 but in reality thesespicules prove under close and careful examination to be small portionsof the metal itself which have become separated from the mass, and nomatter for how short a time such a separation may have been they becomesurrounded with a film of oxide, which prevents perfect reunion with themass. It seems to be the same natural cause which is antagonistic to thesoldering and welding of aluminium in its pure state. Another serioustrouble exists in casting the said aluminium composition, which is thegreat contraction while cooling. Its shrinkage seems to be nearly doublethat of other bronze compositions. Furthermore, a mass of thiscomposition cools very unequally. If cast in large blocks, the outsidecongeals much more rapidly than the center, which causes a drawing awayfrom the pattern or mold, thereby producing imperfection. Pressureapplied to the metal through a gate or runner, as it is done by any ofthepresent known methods, will not prevent it, because the gate orrunner is always smaller than the mass, and consequently congeals soonerthan the center of the mass. In the ordinary way of casting aluminiumbronze in very open coarse sand molds this defects is greatly remediedby providing numerous sprues in the center; but such open coarse moldswill not answer for castings on whose surface the finest line of thepattern must be well defined.

By the use of my herein-described apparatus, and by the fundamentalprinciple of operation, I fully overcome the above-mentioneddifficulties of casting aluminium bronze into a perfect die.

The apparatus is plainly shown by the drawings.

The fundamental principle of operation on which success depends is this:I provide a strong vessel open on the top, and which has the same shapeas the outside of the die or mold to be cast. Such vessel is providedwith a non-combustible lining of weak thermal conductivity. The patternand the interior of the mold having been heated to incandescence, themolten composition is poured into the mold. After being poured into saidvessel time is given for the metallic portion to come to a perfect restand unity, and for the dross, foam, and other impurities to come to thetop. The said impurities are then removed by the operator. The yet openmold is now seen full of clear molten metal. The frame G, with the claypattern H, is then placed (face down) on top of the frame A. The platenP, being now depressed, holds the frame G, with its inclosed pattern,down and tightly closes the mouth of the mold. Continued depression nowof the platen P operates to force the frame G (with its pattern I1) andthe frames A and C downward against the piston E, exercising pressure onthe still fluid or plastic and now absolutely quiescent metal, which,with a clean surface, comes in contact with and is pressed stronglyagainst the pattern, causing said metal to receive a perfect impressionof the same. The contents of receptacle A become congealed on theoutside to a certain extent during the performance of the operations ofcoming to a rest, being skimmed, placing the pattern on top, andapplying the pressure; but the piston E and the block D, being smallerthan the internal size of the mold, will still force easily into the yetfluid center and exercise the desired pressure on the metal, therebyfilling the mold completely, and at the same time taking up andcompensating for the tendency to shrinkage in the center of the casting.

Having now fully described the apparatus in its details and functions,and having laid down and explained the principle on which I operate, Iwill now shortly describe the final operation of casting and pressing adie. The apparatus being complete, as shown in Fig. 1, is placed on aniron plate L, (see Fig. 4,) and the whole inserted in a press M P, whichmust be provided with a projecting platform or base. Such a press mustbe of a capacity to exercise a pressure of about four hundred pounds toeach square inch of the surface of the die to be cast. This done, theinterior lining of the frame A is again heated to expel all moisture.The pattern H in the frame G is then removed and also reheated(preferably by means of a blow-pipe) and laid in readiness to bereplaced quickly on top of the frame A. In the meantime, or previouslythereto, the aluminium composition has been melted in a proper suitablefurnace. Then I fill the frame or receptacle A with the melted metal,making, however, proper allowance for the room or space which will beoccupied by the projection of the pattern-that is to say,for theformation of a large deep die the pattern has a correspondingprojection, which takes the required space in the frame A. To fill theframe A completely in such a case would cause an overflow when thepattern is put in place, which would cause an objectionable flange 011the die, and this would be an impediment to its removal from the frame.When the frame A is filled as stated, the metal will bubble and showsome agitation, which will, however, subside in afew seconds. As soon asthe fluid metal rests quietly all the foam and impurities are quicklyskimmed off by means of a suitable tool N, (see Fig. 2,) so as topresent a perfectly-clear mirror-like surface of the fluid metal.pattern in the frame G (see Fig. 3) is quickly placed on top (face down)descending gently to its place, guided by the steady-pins g, and therebyclosing the mold. The whole apparatus resting on the plate L is thenplaced under the screw-press P, which is promptly brought intodepressing action to the extent required, according to the size of thedies surface. (See Fig. 4c.) The continued action of the press P willmove the combined frames A, G, and C against the stationary block D,which will force itself into the rear center of the molten mass, whichis the last spot to cool and prevent the central shrinkage and becomeitself a part of the die. In the course of a few minutes, during whichtime the pressure is kept up, the metal has cooled enough to be removedby taking the apparatus apart and knocking the die out of the frame A.Should portions of the claypattern adhere to the die, they may be easilyremoved by a little harfd-work and proper tools. When the clay isremoved, it will be found that the die Then the clay or mold is aperfect intaglio copy or counterpart of the claypattern-a copy perfectand true, for example, as in the electrotype production of a' coppershell. The whole surface of the die is free from anyimperfections ordefects, and the whole body of the die is as solid. and free fromblow-holes as if it had been forged.

In conclusion, I wish to state that I do not confine my claims to theexact type of appaia tus herein described. By many modifications of theapparatus which will not require special faculties of invention the samemethod may be adapted to sundry shaped castings of which it is requiredto have one side of a perfection requiring special hand labor to bringit to such. Forillustration, the frame Gmay inclose a clay mold formedfrom a pattern which presents two or three ornamented sides or of apeculiar shape. By observing the same rules and principles described thesame good resultsare obtained. A mold of an object inclosed in frame Gis just as perfectly filled by pressing the metal upward. It remains thesame Whether the frame G holds a clay relief pattern or a clay mold ormatrix. For example, I produce fine results in cast ing artificialteeth-molds by a slight modification of my apparatus. Such teeth-moldspresent three sides, which have to be reproduced just like the originalmold.

In some applications of my system the piston E may consist of a falsebottom or follower so formed. and of such material as after havingdischarged its functions of forcing the molten and gradually cooling andshrink ing metal against the pattern-face to be withdrawn bodily fromthe cast die and not contribute to the permanent substance of such die.The pressing action may of course be equally well accomplished by a viceversa of the described action, in which the piston or false bottom iselevated against the superincumbent members, which are held stationary.The extraneous pressure may be derived from any customary source, suchas a hydraulic pump, a toggle, or a lever.

Having thus described my invention, the following is what I claim as newtherein and do sire to secure by Letters Patent:

1. The process or method of forming a die of aluminium composition oralloy, which con sists in filling a mold (which is open at top and has afalse bottom) with the molten metal or composition, which is thenallowed to settle, skimming off the impurities, closing the open top ofthe mold with the pattern, (face downward on the clean molten metal,)and pressing the said parts downward against said false bottom, or viceversa, as and for the purposes set forth.

2. The processor method of forming a die of aluminium composition oralloy, which consists in filling an open mold with the molten metal orcomposition, which is then allowed to settle,s kimming off theimpurities, closing the open mouth of the mold with the pattern, and sodepressing said parts as to cause the entrance into the central bottomportions of the metal of a two-part plug or piston whose upper portionremains within the die or casting as an integral portion thereof, in themanner explained.

3. A baked-clay pattern fastened within and protected by a surroundingframe of stronger material, in'the manner and for the purpose described.

4:. In combination with a mold and piston, the separable block D,for thepurpose explained. 5. In combination with the mold A and piston E, theflanged frame 0, serving asa packing-box for said piston.

(3. The combination of the frames A and O, the piston E, and theseparable block D, for the purpose explained.

7 The combination of frames A and G with piston E, and a baked-claypattern held. in a frame G, forming a complete mold, to which pressurecan be applied in the manner specified.

S. The combination of the following elements, to wit: (a) the base orbed plate L, the piston or false bottom E, which rests upon said base,and the springs K, which also rest upon said base 3 (b) thesuperincumbent members which rest upon the springs K, an d which consistof the frame 0, with its packing it, the frame A, with its packing J,andthe frame G, with its inclosed pattern H; a platen P, depressed byscrew or its equivalent, the whole being combined and operatingsubstantially as set forth.

9. The separable block D, having downwardly-fiared orifice d, for thepurpose specified.

10. As a new and useful article of manufacture, the die of aluminiumalloy or composition, substantially as set forth.

CHARLES GRASSER.

Witnesses:

J. J. 0. SMITH, V. XV. SCOTT.

